6/2/2016 CHAPTER 15 COMMUNITY INTERACTIONS

6/2/2016 COMMUNITY INTERACTIONS Organisms live where they can fulfill their needs. Organisms live where they can fulfill their needs. An organism’s habitat refers to where an organism lives in an ecosystem. An organism’s habitat refers to where an organism lives in an ecosystem. The specific functional role an organism has is its niche. The specific functional role an organism has is its niche. The way it goes about living its life The way it goes about living its life What the organism does, and what is done to the organism What the organism does, and what is done to the organism Includes both biotic and abiotic factors Includes both biotic and abiotic factors

6/2/2016 KINDS OF INTERACTIONS Predation – a predator captures a prey, kills it, and eats it. Predation – a predator captures a prey, kills it, and eats it. Elimates poorly adapted individuals Elimates poorly adapted individuals Parasitism – the host is harmed and the parasite benefits Parasitism – the host is harmed and the parasite benefits Parasites can live inside or outside the host. Parasites can live inside or outside the host. Mistletoe, tapeworms, fleas Mistletoe, tapeworms, fleas Vectors are organisms that can spread parasites. Vectors are organisms that can spread parasites. Mosquitoes, ticks Mosquitoes, ticks

6/2/2016 KINDS OF INTERACTIONS Commensalism – one organism benefits and the other is not affected. Commensalism – one organism benefits and the other is not affected. Remoras and sharks Remoras and sharks Tree mosses Tree mosses Mutualism – both organisms benefit from one another Mutualism – both organisms benefit from one another E.coli and humans E.coli and humans Bees and flowering plants Bees and flowering plants Competition – an interaction between organisms in which both organisms are harmed to some extent. Competition – an interaction between organisms in which both organisms are harmed to some extent. Weeds and garden plants Weeds and garden plants Occupying different niches helps reduce competition Occupying different niches helps reduce competition

6/2/2016 CYCLING OF MATERIALS IN ECOSYSTEMS Only sunlight energy comes to the earth in a continuous stream Only sunlight energy comes to the earth in a continuous stream Returned to space as heat Returned to space as heat Drives all biological processes Drives all biological processes Inorganic matter combines to form organic matter Inorganic matter combines to form organic matter Decomposers recycle dead organisms into inorganic matter. Decomposers recycle dead organisms into inorganic matter.

6/2/2016 THE CARBON CYCLE Carbon, nitrogen, oxygen, hydrogen, and phosphorus are commonly recycled when an organism dies. Carbon, nitrogen, oxygen, hydrogen, and phosphorus are commonly recycled when an organism dies. Carbon and oxygen combine to form carbon dioxide. Carbon and oxygen combine to form carbon dioxide. Used to make carbohydrates through photosynthesis Used to make carbohydrates through photosynthesis Producers are fed on by herbivores, which are fed on by consumers Producers are fed on by herbivores, which are fed on by consumers Waste products are broken down by decomposers and are recycled back into carbon and oxygen sources Waste products are broken down by decomposers and are recycled back into carbon and oxygen sources Some is released into the atmosphere Some is released into the atmosphere

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THE WATER CYCLE Water molecules are the most common molecules in living things. Water molecules are the most common molecules in living things. Used in photosynthesis Used in photosynthesis All metabolic reactions in organisms take place in the presence of water. All metabolic reactions in organisms take place in the presence of water. Also used to carry nutrients Also used to carry nutrients Water is recycled as a result of normal physical processes Water is recycled as a result of normal physical processes Evaporation Evaporation Rain Rain

6/2/2016 NITROGEN CYCLE Nitrogen is an essential element for amino acids, nitrogenous bases, ATP, and nucleic acids. Nitrogen is an essential element for amino acids, nitrogenous bases, ATP, and nucleic acids. Most common gas in the atmosphere Most common gas in the atmosphere Not usable to most organisms Not usable to most organisms Symbiotic nitrogen-fixing bacteria convert atmospheric nitrogen to a usable form Symbiotic nitrogen-fixing bacteria convert atmospheric nitrogen to a usable form Found on the roots of certain plants (beans, clover, peas, etc.) Found on the roots of certain plants (beans, clover, peas, etc.)

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NITROGEN CYCLE Plants use nitrogen to produce amino acids and other compounds. Plants use nitrogen to produce amino acids and other compounds. Plants also gain nitrogen through decomposing bacteria that convert organic compounds to ammonia. Plants also gain nitrogen through decomposing bacteria that convert organic compounds to ammonia. Nitrifying bacteria also convert ammonia into nitrates that some plants use. Nitrifying bacteria also convert ammonia into nitrates that some plants use. Most plant use either ammonia or nitrate compounds. Most plant use either ammonia or nitrate compounds. Animals gain nitrogen through the foods they eat. Animals gain nitrogen through the foods they eat. Used to make amino acids, proteins, nucleic acids Used to make amino acids, proteins, nucleic acids

6/2/2016 THE PHOSPHORUS CYCLE THE PHOSPHORUS CYCLE Phosphorus is very important to biological molecules such as DNA and membrane structures of cells. Phosphorus is very important to biological molecules such as DNA and membrane structures of cells. Also important in bone and tooth development. Also important in bone and tooth development. The primary source of phosphorus is rock from where it is released by erosion and dissolved in water. The primary source of phosphorus is rock from where it is released by erosion and dissolved in water. Plants absorb phosphorus from water Plants absorb phosphorus from water

6/2/2016 THE PHOSPHORUS CYCLE Animals obtain their phosphorus by consuming animals and plants. Animals obtain their phosphorus by consuming animals and plants. Also present in animal waste products Also present in animal waste products Made available by decomposers from dead organisms. Made available by decomposers from dead organisms.

6/2/2016 HUMAN ACTIONS ON COMMUNITIES All organisms are connected by various relationships All organisms are connected by various relationships Demand for farmland, real estate development, and increasing human population has resulted in the disruption of many communities Demand for farmland, real estate development, and increasing human population has resulted in the disruption of many communities The main problems include introduction of exotic species, predator controls, habitat destruction, pesticide use, and biomagnification The main problems include introduction of exotic species, predator controls, habitat destruction, pesticide use, and biomagnification

6/2/2016 INTRODUCED SPECIES Many of the organisms that live in the U.S. are considered foreign species Many of the organisms that live in the U.S. are considered foreign species Most were intentionally introduced Most were intentionally introduced Domesticated plants and animals Domesticated plants and animals Cattle, horses, pigs, goats, and many grasses have been introduced Cattle, horses, pigs, goats, and many grasses have been introduced Have altered the original ecosystems that were once present Have altered the original ecosystems that were once present Can be dangerous if native species have no defenses to foreign species Can be dangerous if native species have no defenses to foreign species Dutch elm disease, kudzu vines, zebra mussels Dutch elm disease, kudzu vines, zebra mussels

6/2/2016 PREDATOR CONTROLS During early wildlife management, predators were heavily hunted to help increase population sizes of game species During early wildlife management, predators were heavily hunted to help increase population sizes of game species Pests became an increased problem (mice, rabbits) Pests became an increased problem (mice, rabbits) Predators help control populations sizes of both their prey species and smaller, nonprey species Predators help control populations sizes of both their prey species and smaller, nonprey species Without predators, prey can become a nuisance or a threat Without predators, prey can become a nuisance or a threat

6/2/2016 HABITAT DESTRUCTION Some communities are fragile and easily destroyed by human activity Some communities are fragile and easily destroyed by human activity Others are more resistant Others are more resistant The more complex an ecosystem is the more likely it is to recover after a disturbance. The more complex an ecosystem is the more likely it is to recover after a disturbance. Extinction or endangerment of species is usually caused, indirectly, by destruction of their natural habitats by humans Extinction or endangerment of species is usually caused, indirectly, by destruction of their natural habitats by humans farming, grazing, forestry, development, etc. farming, grazing, forestry, development, etc.

6/2/2016 PESTICIDE USE Many pesticides have been introduced to control specific pests. Many pesticides have been introduced to control specific pests. One is DDT – a poison that was used to kill a variety of insects. One is DDT – a poison that was used to kill a variety of insects. Was very successful, but some organisms developed resistance Was very successful, but some organisms developed resistance Very toxic to mammals, birds, and other organisms. Very toxic to mammals, birds, and other organisms. Banned in the U.S. in 1970s, still used in Mexico Banned in the U.S. in 1970s, still used in Mexico

6/2/2016 BIOMAGNIFICATION Refers to the accumulation of a toxin in the bodies of organisms that are not the target of the toxin. Refers to the accumulation of a toxin in the bodies of organisms that are not the target of the toxin. DDT is a stable compound (slow break down) and was found to accumulated in the bodies of organisms. DDT is a stable compound (slow break down) and was found to accumulated in the bodies of organisms. Becomes more concentrated moving up the food chain Becomes more concentrated moving up the food chain Animals high in the food chain accumulated lethal levels of DDT (eagles, pelicans) Animals high in the food chain accumulated lethal levels of DDT (eagles, pelicans) Interferes with the development of hardened egg shells Interferes with the development of hardened egg shells Banned due to its severity Banned due to its severity

6/2/2016 BIOMAGNIFICATION OF DDT

6/2/2016 CHAPTER 15 COMMUNITY INTERACTIONS

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